The objective of the investigation proposed here is to develop phosphate potentiometric electrodes for the rapid diagnostic profiling of the phosphate clinical chemistry constituents which are important indicators of body malfunctions. Direct sensing phosphate electrodes or probes will be developed for the assay of: inorganic phosphate, acid phosphatase, and alkaline phosphatase. These clinical electrodes will be made by adapting a recently developed potentiometric ion-selective phosphate electrode (Type I electrode) to biological matrixes for the assay of body inorganic phosphate and by sensitizing the new Type I electrode with interposed chemical reactions (Type II electrode) for the assay of acid and alkaline phosphatase. The inherent simplicity, speed of response, and compactness of these electrodes should permit diagnostic profiling with phosphate electrodes in a manner as simple as a pH measurement-replacing the long, tedious, conventional methods of analyses.